As of 2021, seven million people in the UK live with either a cardiovascular or respiratory long term health condition1. These conditions are associated with poor health outcomes, reduced quality of life, increased number of hospitalisations, and premature death. Effective management through medication and lifestyle changes, particularly increased physical activity, can reduce the risk of poor outcomes. Regular physical activity offers many benefits to an individual, including improved physical and mental health, cardiovascular outcomes and survival. Engaging in regular physical activity can also enhance cardiovascular fitness, which helps prevent the progression of long-term conditions (LTCs).
Physical activity guidelines for the general population recommend at least 150 min of moderate-intensity exercise per week2, and often similar recommendations exist for those living with chronic conditions3,4. Those living with LTCs receive the same benefits from exercise as those without5,6,7. Despite the guidelines, many individuals with LTCs fail to meet current recommended activity levels8. Exercise activities are often prescribed for individuals with respiratory and cardiovascular conditions for the specific purpose of mitigating the exacerbation of symptoms related to their disease. This may be, for example, exercise to improve cardiovascular health in heart failure patients, or reduce BMI and increase glucose control in people with type 2 diabetes. Those living with LTCs may be limited in their ability to engage with physical activities due to their LTC, and many may be under medical supervision before and during engagement of physical activity.
One important barrier to physical activity among individuals with LTCs is the risk of exposure to air pollution during outdoor exercise, such as walking, cycling, or running. Physical activity increases ventilation (breathing) rates, leading to higher inhaled doses of pollutants such as particle matter (PM2.5), nitrogen dioxide (NO2), ozone, and ultrafine particles9,10,11 This can exacerbate respiratory symptoms and contribute to reduced lung function, particularly among individuals with asthma and COPD12,13,14. Negative cardiovascular effects have also been reported, including altered vascular function, blood pressure, and cardiac arrhythmias15,16,17.
Carefully controlled physical activity is possible and can be beneficial in people living with LTCs18,19. Mobile phone applications (apps) can be used to support behavioural change in those with LTCs, such as to aid increasing physical activity levels20. As well as being in control of LTC symptoms and flare ups, another important factor to those living with LTC is being able to assess the air quality in the local area prior to outdoor exercising21. In addition to direct physiological effects, individuals with LTCs may experience additional behavioural barriers due to fear or concern regarding outdoor exposure to pollutants. For example, thunderstorm asthma is an example of a condition influenced by extrinsic environmental exposures. Other extrinsic environmental factors include meteorological factors such as high pollution levels, extreme temperatures, and aeroallergens22,23. Pollen exposure more broadly can act as a trigger for respiratory symptoms and exercise-induced bronchoconstriction, particularly in individuals with asthma or allergic conditions. Thunderstorm asthma represents a more acute form of this interaction, where meteorological conditions and high pollen levels combine to trigger severe exacerbations24,25. Air pollution might influence people’s attitudes and behaviours towards exercise. Evidence suggests that people may reduce or avoid physical activity during episodes of high air pollution, and air quality alerts may significantly influence people’s decisions to exercise outdoors26. In addition to the physical risk of such extrinsic exposures, the fear of potentially encountering these factors might dissuade people with LTCs from engaging in physical activity, making it imperative to be aware and forewarned of these extrinsic conditions potentially occurring.
The Personalised Space Technology Exercise Platform (P-STEP) smartphone app was designed to address this gap by integrating real-time (hourly) air quality data with personalised exercise guidance, allowing individuals to plan safer outdoor activities. The P-STEP app, developed with funding from the European Space Agency, brings together tailored exercise guidance, taking into account an individual’s LTC, while also providing up-to-date information on air quality. The air quality information captured by the app includes a variety of emissions that impact health and activity through short (hours to days) or long-term (months to years) exposure. Air pollution is a complex mixture of gases and particles originating from a wide range of human activities such as vehicle emissions, industrial processes, residential heating, and power generation, as well as natural sources including wildfires, volcanic activity, sea spray, and desert dust27. Once emitted, these pollutants can be transported across large distances, with meteorological factors such as wind speed, direction, boundary layer height, and temperature strongly influencing the dispersion and accumulation of particles28,29. The P-STEP app provides real-time data on several pollutants of particular relevance to health. Particulate Matter (PM) is monitored in two fractions: PM₁₀ (particles with a diameter smaller than 10 μm) and PM₂.₅ (particles smaller than 2.5 μm). PM₁₀ includes larger particles such as dust, pollen, and sea salt, which primarily affect the upper airways and may aggravate respiratory conditions. In contrast, PM₂.₅ consists of finer particles from combustion sources and secondary chemical reactions, which can penetrate deep into the lungs and bloodstream, and is strongly associated with cardiovascular disease, respiratory illness, and increased mortality30,31,32 Nitrogen dioxide (NO₂) is emitted primarily from fossil fuel combustion in the transport sector, energy production, and residential heating. NO₂ contributes to the formation of secondary pollutants such as ozone and nitrate aerosols and is associated with airway inflammation, impaired lung function, cardiovascular disease, and increased incidence of asthma, especially in children33,34. Ozone (O₃) is a secondary pollutant formed through photochemical reactions involving nitrogen oxides (NOₓ) and volatile organic compounds (VOCs) in the presence of sunlight35 Exposure to ozone has been associated with lung inflammation, airway hyper-responsiveness and adverse effects on both the cardiovascular and respiratory systems36,37.
Air quality data within the P-STEP app is provided through EarthSense’s MappAir model ( which combines ground measurements, satellite data, emissions, and meteorological inputs to produce high-resolution, real-time air quality information at 100 m resolution in the United Kingdom and 10 m in the Leicester. Data are updated hourly to give users accurate, location-specific pollution levels.The P-STEP app will access the user’s location (with permission) using satellites around Earth Global Navigation Satellite System (GNSS) in order to help them plan when and where to exercise. The app aims to advise users on where in the local area they can exercise in the cleanest areas possible. P-STEP aids in this goal by helping users to find the cleanest areas local to them and giving them access to a 72-hour forecast to find the optimum time and place to exercise. Long-term studies suggest there could be benefits of regular exercise even at moderate air pollution levels38,39.
The app allows individuals to plan exercise routes (walking routes) in order to minimise their exposure to air pollution, by using the information to help them avoid higher polluted areas. Alerts were integrated into the app to bring the user to attention high levels of pollution in the local area. The user was also able to look at the 72-hour forecast in a specified location, allowing them to plan their activities around times where their local area was highly polluted. The app collects data on the time individuals have spent exercising, to reassess their exercise targets which are calculated by a bespoke evidence-based algorithm designed by a team of health experts. This algorithm takes into account the individuals characteristics, LTC, and previous levels of exercise. The user can access a range of features in the app, including recording their walking route, planning when/where to go walking by being provided with a 72-hour forecast, achieve walking badges/milestones, save their favourite walking routes. For such an application to be successful in real-world settings, it must be both usable and acceptable. People with different LTCs might be affected in different ways by different pollutants, therefore filters and personalisation exist to ensure the app is adaptable for the individual.
This feasibility study is crucial as it evaluates the practical implementation of the P-STEP app. By assessing usability engagement and feasibility outcomes, this study will inform the refinement of the app and the design of a future clinical trial. Understanding the barriers and facilitators to technology-driven behaviour change will help optimize future digital health interventions, ensuring their accessibility, relevance, and long-term survival while also improving health outcomes for individuals.
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